The goals of this research project are to synthesize polynucleotides of known sequences for the studies of their structures, DNA-protein and DNA-drug interactions and of eukaryotic gene expression mechanisms, and to make improvements in the solid-phase synthesis by the phosphotriester method. The specific research goals covered by this application are as follows: 1. Synthesis of a large amount of short polynucleotides (approximately 100 mg) for use in X-ray crystallographic and NMR spectroscopic studies. This synthesis includes various designed sequences of short DNA duplexes, EcoR1 recognition site, lambda-repressor binding site and modified dodecanucleotide (dCGCGAATTCGCG). 2. Synthesis of polynucleotides for use in preparing mutants of eukaryotic genes and making affinity columns to fish out the proposed RNA splicing complex. These synthetic polynucleotides will be used for the studies of eukaryotic gene expression, including initiation of transcription, splicing and polyadenylation. 3. Improvement of the solid-phase synthesis of polynucleotides towards automation of the whole synthesis process to facilitate the research project mentioned above.